The onset of hemorrhagic shock is a major cause of death in emergency departments and trauma centers. Currently there is no clinically accepted quantitative monitor of the onset of hemorrhagic shock. Death from hemorrhagic shock results from diminished capillary blood flow and the resultant failure of the body to oxygenate major organs. The long-term goal of this proposal is to develop a sensor patch (CBFM) that attaches to a patient's skin and continuously monitors capillary blood flow and, in conjunction with other monitors, predicts the onset of hemorrhagic shock. The sensor is based upon diffuse correlation spectroscopy (DCS). DCS measures fluctuations in red or near-infrared (NIR) light scattering as blood cells move in the capillary bed. Using correlation analysis, DCS extracts the characteristic time constants due to mean blood flow velocity. The device can also monitor heart rate, arterial or venal blood flow, and blood oxygenation. The aims of the proposal are: 1 - Design and build a prototype CBFM, 2- Demonstrate the ability of the prototype device to measure capillary blood flow in pigs and determine whether capillary blood flow measurements are a good early indicator of the onset of hemorrhagic shock (hypovolemia), 3 - Create initial design of Phase II prototype, 4 - Write final report and Phase II proposal. PUBLIC HEALTH RELEVANCE: The onset of hemorrhagic shock is a major cause of death in emergency departments and trauma centers. Currently there is no clinically accepted quantitative monitor of the onset of hemorrhagic shock. Death from hemorrhagic shock results from diminished capillary blood flow and the resultant failure of the body to oxygenate major organs. The goal of this proposal is to develop a sensor patch that attaches to a patient's skin and continuously monitors capillary blood flow and, in conjunction with other monitors, predicts the onset of hemorrhagic shock.